Provide `key`/`object_name`/`blob` attribute in CloudPath

[Dev-iL]

Suppose I have a remote path as follows:

gcs_path = GCSPath("gs://bucket-name/A/B/C/filename.tar.gz")

I'd like a way to get a UPath object that represents the location in the bucket, e.g.

UPath("A/B/C/filename.tar.gz")

I'd like to avoid my present workaround of "/".join(gcs_path.parts[1:]) since it's not immediately clear what this code is doing.

Possibly related to #170

[ap--]

Can you provide more context?

The following style for creating paths is implemented for s3, gcs and az object storage:

>>> import upath
>>> upath.UPath("A/B/C/filename.tar.gz", protocol="gs", bucket="bucket-name")
GCSPath('gs://bucket-name/A/B/C/filename.tar.gz')

[Dev-iL]

I need the other way around.... I have a GCSPath object, now I'd like to extract the path itself (i.e. without the protocol and bucket) by using some of the methods/fields of the object. Is there a way to do that?

[ap--]

So from my understanding, to stay in the google storage vocabulary, you'd want the OBJECT_NAME, whereas right now you can only retrieve the PATH_TO_RESOURCE = BUCKET_NAME/OBJECT_NAME.

This will become generally available once either relative_to behaviour is fixed (which requires some more thought before rolling out) or url chaining is implemented #28 (you can then use dirfs to remove the prefix from path.)